Modern electronic signals is becoming increasingly complicated and diversified, and the information carried by the signals is diverse, random and of large amount. How to effectively extract the information, i.e. how to realize real-time acquisition and analysis of wideband, transient and non-stationary signals has brought challenge to modern signal measurement. To meet the challenge, the time-domain measurement based on real-time sampling and processing has attracted attention widely and has become the mainstream of modern signal measurement.
In time-domain measurement, the digital storage oscilloscope (DSO) has been widely used. With the increasing complexity of measured signal, the capture capacity for abnormal signals, such as occasional signal and transient signal, has become an important indicator of evaluating the performance of DSO's data acquisition.
Generally, the capture capacity for abnormal signal can be improved by two methods: one is just improving the waveform capture rate (WRC) of DSO, the WCR can be defined as the number of waveforms that can be captured in a unit time (wfms/s), and the higher the WRC is, the bigger the probability of capturing abnormal signal by DSO is; another is finding the abnormal or occasional signal through long time's waveform capture by infinite persistence. However, in the two methods, long time is needed to capture the abnormal or occasional signal, therefore, both the two methods are inefficient, moreover, when displayed, the waveforms acquired by multi triggers are superimposed, which make the user difficult to identify and study the abnormal or occasional signal, leading to inconvenience for measurement.
The trigger system of DSO can ensure that the each acquisition start at the positions which are satisfied with the triggering condition. thus the acquired waveforms are synchronized. For the periodic signal, the acquired waveforms are overlapped, a stable display can be obtained. Furthermore, the trigger system of DSO can not only ensure the stable display of periodic signal, but also can ensure the capture and display of the signal with specific features. In a word, the trigger has two main functions: one is ensuring waveform's stable display, another is capturing the interested signal. General speaking, the trigger is used to control the storage and display of DSO.